He half-opened the casement window on the street and levelled his revolver.

他半开着临街的平开窗， 举起左轮手枪。

The casement windows allow warm air to be  funnelled from down below up into the high level rooms and out through the courtyard space  this allows the lower rooms to be cool through a Venturi effect of circulating hot air.

平开窗使暖空气从下向上流入高层房间，并通过庭院空间流出，这使得较低的房间可以通过循环热空气的文丘里效应来冷却。